There is a need for controlling a dose of irradiation in a radiotherapy such as X-ray or gamma-ray and thus, a so-called collimator(collimator) is used. A representative form of this collimator is a multi-leaf collimator and this traditional multi-leaf collimator uses a driving mode wherein a plurality of leafs are moved individually, a dose of the radiation maintains or modifies a specific shape of the region to be delivered as a space form, and the dose is deliverd as time-based movement.
The said traditional multi-leaf collimator is necessarily attached to and used in almost all radiotherapy instruments in a radiation therapy at present, but there is an inconvenience that a plurality of leafs(leaf) are operated by seperately and directly moving. In addition, the said multi-leaf collimator is expensive as an imported article, is dificult to be self-produced, and when it is attached to and used in the radiation therapy, a plurality of leafs(leaf) maintain the space form by moving them every movement, but they do not change their position, only except for changing the said space form in place.
Therefore, it is ungent to introduce the technology into Korea, which can display a high performance per price in a formation of a complex dose region, or a control of a short or irregular dose intensity, as an instrument which can be manufactured by only Korean technology, and display the same degree of performance at a very lower price than the multi-leaf collimator.
Furthermore, when radition beams are passed by a plurality of leafs(leaf) in the traditional collimator, since the beams tend to spread as being far away, the spreading angle and an energy property should be considered, but said multi-leaf collimator does not consider these facts, and thus it leaves something to be desired in a delivery of the correct dose and intensity of radiation.
In addition, a particle radiation such as a proton beam or carbon ion beam has a specific dose delivery property such as Bragg peak(Bragg peak) unlike X-ray and thus has an advantage for protecting the around normal organs simultaneously with delivering much dose of radiation to the tumor. That is, as shown in FIG. 8, when considering the property of dose delivery of the particle radiation in a center, an Energy-transfer near the surface of medium greatly occurs in X-ray, but a high Energy-transfer (Bragg peak) occurs only in the special depth in the particle beam.
And, the particle radiation therapy generally treats a patient by spatially modulating the particle beam through dual scattering and range modulation(range modulation) mode for depth of penetration of beam. In this case, since forms of tumors are different from every patient, the particle radiation therapy uses a compensator regulating a distribution for the depth of penetration of the particle radiation in order to deliver the radiation dose only to a target. The particle radiation passing through a thin place of thickness of the compensator penetrates to a deep place in a body and since the depth of penetration becomes shallow in the body when passing through a thick place, the distribution of the radiation dose becomes coincident with the form of a depth direction of a tumor. That is, as shown in FIG. 9, since the depth of penetration of the particle beam in the body becomes deeper in the place wherein the thickness of compensator is shallow, and the depth of penetration becomes shallow in the place wherein the thickness of compensator is thick, the distribution for the depth direction of the radiation dose can be regulated.
In the above compensator, a traditional compensator processes solid polymer materials such as PMMA (Polymethyl Methacrylate) and the like or soft materials such as wax and the like by using a milling machine to fit to the treatment site of the patient and use it in the treatment of the patient. But, since such the compensator is patient-specific, it should be individually produced for each patient, and cannot be reused in other patient after the treatment, as well as even in the same patent, when the beam direction used in the treatment is increased, the same number of compensators should be produced. Therefore, the continuously high expenditure for the material cost is occured, and since the time required for manufacturing the compensator is too long, there are problems in treating many patients at the same time or in rapidly treating the emergency patient. In addition, when two or more of beams are used, there is a risk that a treatment is to be made while reversing compensators each other by a human error.
As mentioned above, since the proton therapy should produce and use high energy protons, it cannot be used in a hospital equiping with a seperate production facility. In addition, although the proton treatment is possible, in order to compose the dose distribution necessary for the tumor tissue via a treatment plan, the corresponding compensator and damping material being optimized to the tumor tissue shoud be produced, but it is the form wherein the treatment is made after the production period for 1 day normally as often, for 3 days when delaying. Although the problem of delaying is a part being resolved by the normal effort, there is an inconvience that all damping materials suitable for tumor tissues should be produced in each patient.